Electric bell



July 27, 1943.

L. J. STERN ELECTRIC BELL Filed Oct. 2, 1941 2 Sheets-Sheet 1 "NVENTOR Lay/5 J 575/? ATTORNEY y 1943- L. J. STERN- 2,325,081

ELECTRIC BELL Filed 001.. 2, 1941 2 Sheets-Sheet 2 I mllmrll b )1 @lnm I N VEN TOR l FI V/J J 57:???

TTORNE Y f; Planet July 37, 19 437 Other objects 7 gong its natural p'e structure which'may be manufactured 'and' as:

.sembled at low cost. p V p I 7 "Afurther object is the provision of a novel jy ofbell for alternating current operation will appear in the fllowing"de' scription.

A' preferred embodiment of the invention describediherein relates to'an' alternating current bell of the contactless type, Known bellsof this A I kind "fall into two" general groups, namely;

' plungerjvtype bells and polarized bells.

The bells ofthe' plunger class usually' consist of an electro-magnetic system; such as a s'olenjoidl In thistype of hell the plunger or'fthe armature o is heldouteof thef magnetic'field'by a'j'jspring of sufficient] strength to give 'the v armature or plunger a'natur'al p'rio d QfV'lZ O cycles per'second orgreateit. In thistype of mechanism when an electromotiye forceiof fifl cyclesper second is applied to the winding the armature or plunger "will respond and pull :into thefieldduring half" of each cycle or' ihjother'words, will attempt to vibrate at 120 strokesperjsecond, This synchroe inism' r vibrationwithth' applied EjMl Rwill', "of course, only-be '=true' 1 -whn. the plunger or Yarmature .is vibrating freelyiandfnot striking I l V ELllCIRJd 13ELL' "If 7 p :Lewis Jnstermfldriang Mich;-;assi;g"r 1or, by iniesne l n .gassi n e t Schwarze E cc i lcomranyiw 1 Chicago, -r im a inerr hiw 1 1 n 1 i. v Application'qctober -2, l llf s erial N 413,257" p o a rc i ismi -'7)? p inventionrelates to electric bells and has wfor its object to provide a-simple and reliable bell power input is greatly r'ducedzy againstih ong. When it strikes against the consisting largely of the "spring tending to pull ithe arn'iature out ofthe magnetic field; then'at euralfreduency of t hejgong'fand the working fric Y tion of the'parts, .all of which operate in the re-' yerse direction; fr iii" the "in'agneton otive' force generated .by thejappliedfialternating'i'current;

It will be readily seen thatthe Value of the restraining forces; [The"restraining-foreej con} sisting of the pull generated by thefspring will be quitelarge owing to thefact that this fo'rce w d' willbejinterfere'd with i andtheactualTrate qf yibrationwillfbe deter? Ff mined by the 'resultant or all 'thefforce's' at" play must bei oi sufiici'ent alue to'giiie the'vibratin system a natural frequency of atZIeastlZO'cycle's 7 persecond.

v i For this reason bells'constructed to operate Qunder this principle require a largepower input mende and trie spr'ing solenoid 7 o armature "to-'whic the} plunger 7 is attached is very much smanerand' therefore the:

In additionj to' the. electromagnetic system there is,- atiprsent; in the pol'ari'z'edmechanism' a pernianentimagnetj th epol'es-"of whi'char'e' 'arrangdwofstiii;Par-unidirectional magheto- :rnoti ve forcezin the -plunger in' theiease ofsole f l n'oids'; and in the 'electronrag iets themselves where that-type of construction is used.;; v

Q"During one-half of the cyclethe magnetomo"-v t ive fi'oree generated by the applied alternating scurrentjwill befiin the same direction :as' the. rriag'n'etomotive 'fo rcegenerated by the pe'rnia v nentama'gnet-andiin the other half'oftheficycle it will :be in the'opposite'direction so that the netzresult will be-a magnetoiriotive for'ee equal to I .the su -or that caused by-the permanent mag- V net an'dthatgeneratedby the coil' windings and "during-the other half of the cycle it will be equal to the difference between thesevalues. In order to et themaximumfl'net value of this difference the-design is usually such that-the magnetomofl tive f'or ce generated by" the applied alternating fcurrent is as near'as' possible tothe maximum which can {safely'be usedwithout-tending to" de-magnetiaethe permanent magnet. Itwill I be apparentthat iflthednagnetornotiv; force g'enerated by the "electromagnet i s too large in I valu'ethemagnetization of thepermanent mag' net will be reduced and will result-in adimi'riu 'tion of the bell intensity.

For "the reason given *above "the vo1ume job- "tainableiromga polarized bell is' limited tome amount of magnetornotiveforce; that can be gen-' eratedelectrically without tending to de mag net 'izethe permanent; magnet; For this 'reasonit and inY-Qrderto developvsuflicieiit magnetomotiye 1 force to operate without the generation'offtQ much heat must be made with'large electro-- "magnetic systems,- It is fornthis reason that'this V typepoof ,bell is only commerciallysatisfactory; in

willbe-"readilyseen"that the possible force .with V; 7 which a gong can; be 'str'uckqis considerably less than" in the type or mechanisrn first deserfibed;

Another disadvantage present in "this t'ype -of constructionis that permanent magnets tend to lose'their magnetisnroveraperiod of years and1are'alsoaffectedin some measure by shock 7 tronia'gnetic' system of the'.polarized 7 bell is 3 substantially; the same {as that'fg'iven v the description abovev -operatef'ata frequencyof onl cycles 'p'er 'se'c ona i'n'stead-of -1-20* yc1e iper required to generate the-=ret1i sirlg this :bll? has to The good featuresof I heretofore described are t'akenadvantage of in the present invention where a rectifier is'used -backward leakag" H I e V deese veethe t1 1 x l ne nlq h q $hfi;.b3ll..- np ei apt almost-any outletgh v" V hell's ancl-it is pessible for the user to install and mixetn se 211 3 5 *QHJ UH PJ QXFFS W ile Peer st ucii n i bl is, o erei in ta l ng i H P hells l 't' The subsequent; nst l ation f the 7 ba l l i nl riee i e s viee o l-ea ieumey Y T manelec'trician,are notrequired in any jurisdicr' tian r eWDQ-Q W Fk-S 1 a uriacconfine h vinelrem ve p l fi f u andlingpossible during shipinent.

I or installation r r t V to replace the perman'ent magnet present in po- 1 lari'zed' bells, 0'13 added to theplunger type. 7' ;;With this" {angefij nt the armature" 6r' 1ung} -er1is only required to operate atfa"natural fre;-

. quencyoffifi cycles per second and therefore the res'traininggforce of the spring can be'as small as that in the polarized bell but-the power input 3 i "is limited only by the'siz of the rectifier a hd' winding employed; This rectifier is placed series with thegcoil' windings and when" an alter i hating current isapjqlied to th e systiri the if rent fiowingkthrough'ithe winding 'consistggf arr; intermittent half wave-with a-so cycle frequency.

i both the "mechanisrns I 2,325,081 I I e ""studiz fextends, 'Ifhe studs "are each provided with a collar is which may he spot welded to. e the underside-0f thebase plate and a. threaded part E 4 depending therefrom. Feet [5 of bridge ifiahave openings through which the studs pass,

and nuts H secur the bridge'to the tops of the bosses.

' e The top of. the bridge has' ja flal ttened part l8 having .in itsmid-section anfioiaening l9 under when it isrealized that at least'50% of-the:

iference, be wee iiki We tribes fiihlh 1 ti he ame; best eio neler zed W 15i? can; be, fastened to the o r; of an :o'u t box .Fig;,l is a,p l an i beeuevenioesga by a i e m n eni e I is a circuit diagral 2 i .a pi ncvi rtp A 2 hl .fi fi .'Thezpresentinvention gonte plates'a bell of 7 mile 7 'flheii v i n w lrn w b jdbgii i 51 ;aid of' the accompanying; drawings t-which V ia i'i'eleefiesi l' 1 Fig.5, each having an opening through which a ten s outwardly mm c Q'pn endbf' the tube 45 mqh eee upwei'fi .50 e e e. a

7 rial fastenedfto't 4i 2}150' supports s'eI arm H fastened the which an- 1in alignment therewith is secured by} Isutable means a nutZEl. a'fiat axially disposed top section 25 which rests f on the part 18 of thebridge is provided with a crjlindric'alwall portion ZTflanged at 28 to overf'liethebaseplate; the flange being turned down at 29' to everlap the edge of the base and prevent ;a ny r n oticn o i thebase and casing in respect A' casing 2'5 having to eaeh other. A" suitable gasket 33 maybe r'la'ced betweenfiange 28 and base platelil. V a ,A; geng 3 i isconcentrically secured' to the eas- Line. by m a 1 e t aiffl sb s 'fih e ,inthe gong hollows'orewfl hai 'ing a'nem onaiheea 34 exteiid sthfough th feyelet and screws into ma ze it hold the'fia tten'ed of the top. pare-i s of 'the'bridge and,

ib'ressthe'fiang'e '25 against gasket eaanq base pram] ill, "so thus byT-aslngle screw the whole structure isheld together Awashertifi, eut'away one uiider surfaee ates so as to clear' theeyelegend distribute pressur 'iis ia'cedbn' t esci'ew between thefhe'ad'there'of and th'uppeff surfice ofthegorig. a a

' solenoid'winding iii 1s 'ii 'bdrted between an le the base; Angle'plate plates 4'] and secure Y e inn; rectifier aspmeans of whilethe o'p' iosite ndjisturned OVEILfa t :21;

he'wall'of he ,casi I 4 of: the. neck gong."

tof n in recesses formed sta'htifillyr'parallel 't fth'ehase where-they, a r'e' secu're'iy hel loy nut 76%] friibolt's filmolded into Ti/ ides 'bi'ridin g' riosts {as well as external connect ine'ans to which a the bellcircuitfc'onsistingof the solenoid foonnected in ts'eris"with the rectiffi r ar attaehed, Ba-g es an bhie circuits there- 'f ii i e he Se r ed an r q e e'h dn up a ly ip'ron'cthf;efear-t 62 fdfi the connector "block which' ishigher than the'topsof bolts er. l

V "A sl efeeea embodiment of a cover plate ac- 3 Bars 58iare arranged tof tinto spring conncti'ng clips held by 'fa term' a1 "block's ecured to the undersidedfa 'coverfpla te "of novel construction da l' tfi to fit oil-"tiet bo'xes of the kindin' general cordingitofthe figsfit vent-10h cons sts of a 46 by spring ie dis lfi lee w h' xr 11d of the tube; The

eeeepner'mm o this 1face'of-th'e coveriplate. A-boss 12', correspond ing in'height to ridge H l1'as-a nut' l3 secured to the under side thereof. A screw 114 extending throughhollow screw 33 and through base plate l is-held by'nut'l3 of" the cover plate; With to anoutlet box T s v The cover plate is secured' td the: outlet box so tha'ti the slotted part, of the guard 'is in the I lowermost l1 position, -thus' r T furnishing additional this arrangement the bell is secured to the cover plate by a single screw. A groove in the body of the screwretains a loosely fitting spring ring 16 which prevents screw 14 from being entirely withdrawn from screw, 33; ,JWitli this arrangement, the-person installing the bell ha s'only. one part to handle. J r Cover plate 'lfiis provided with 'a'n'opening spending opening for the terminal block on base plate 59.. The molded part'of terminal block'Sll is identical with bell'terminal block 55.

7 Block 86, however, hasasturdy brass stripi8| secured by a nut 82 andabolt 83 ineach of two channels formed inthe blocks. The brass strips are formed into U-shaped clips 84 registering I .which is covered by a molded terminal block se: 9 cured to the under side of the plate. The open ing is'dispos'ed to be 'in'register with'the correwith the lower endsof openings formed in the block communicating with the upper surface thereof to receive theconnectihg bars 58 of the, bell which when inserted into the channels spread,

. secured to said basemember, a casing having a topportion and a cylinder shaped wall portion) the clips which exert sufiicient pressure on-the j bars to support'the bell securely bythis means alone, notwithstanding the fact that the single screw arrangement described above is also provided as a support. r I, v Power wires may be attached by means ofrnuts 86 on bolts 83 to clips 84.

A'protecting cover 81' of insulating material Li's pivoted to the terminal block at 88. v The cover V is normally held in position over terminal bolts 83; I r by a small point 88 (shown on the corresponding 4 part of terminal block- 55, Fig. 3), formed on the terminal block which enters a hole, not shown,

in cover 87. When access to the connector memhers is' required the cover may beturned on its .pivot as indicated in the drawings byrdotted lines. With this arrangement coverplate 'mcannot be secured to theoutlet box until cover 8'1 isirestg d to its normal position; a r i protection to the bell from the elements. 3: 'Whilebut oneembodiment of thej i'n'vention 1 has been' disclosed,fiit will be' understoodthat numerous modifications of the same maybe made by those skilled in the 'art without' departing from the spirit and scope of the invention.

What is claimedis:

L 'In' an eleotricbell, a "base member, a bridge securedto said base member, acasing having atop portion and adependin'gwall ortion overlying said bridge said wall portion being-adapted to engage said. base member and to cooperate. therewith to enclose com 1ete1y the Working parts qof saidbell to protect said parts from dust and moisture, e'lectro-magnetic gongoperating means including a striker supported by said base'm'em; ber within said casing, a gong disposed over said casing andsecured thereto by a single eyelet; an

opening in said casing through which said striker I can strike said'gong andscrew meansJpassing throughsaid; eyelet for securing said gong and said casing to said bridge. g '2. In an electric bell, a base member, a bridge disposed on'said' base member overlying said bridge, a gong concentrically. disposed on the out side ofsaid casing having'edges depending'below;

the top portion thereofjasingle eyelet for se; curing said gong to the topportion of said casing, threaded means at the ;top'offsaid?f bridge,

- Cover plate '10 may be provided with a plurality r *of difierently spaced hole arrangements for fastening the plate to various kinds of outlet boxes. In Fig. 4 screws!!!) are shownattaching the cover plate to outlet box 9! member, said threadedportiorr being adapted to.-- screw into a nut secured to asupportingdevice; 4. An electric bellaccordin'g'to claim l'having a terminal block secured to the upper surface of said base member, a pair of metal strips adapt- The bell structure just described may be readily'changed to ,aguarded hell by means of a disc shaped p1ate'92 of greater diameter than base plate l0 provided with a plurality of openingswhich clear projections depending fr'om, the

under side of base plate it so the surfaces of plates 92 and it may be placed in uniform contact with each other. Two r theopenings a plate 92 are disposed to receive threaded members 14 of stud l2, Fig. 5, permitting the plates to be secured' to each'other in concentric relation by nuts 93 onsaid threaded members. A domelike guard member 94, Figs. 1- and 4, provided with a fiat surface 95 adjacent to the edge thereof, to which are welded a number of screws 96 that register with holes inplate'92 is secured to the plate bynuts 91; The edge of the part 95;

mean comprising a single' screw device cooper ating'with said threadedmeans forsecuring said gong and said casing tosaid'bridge' urging' the wall portion ofthe latter against the'surfa'ce'of said'base member, and electro-magnetic gong operating means including a striker supported' by;v said base member within said casing andani opening in said casing through which said striker,

can strike said gong. i l 3. An electric bell according to claim 1 in which i .said screw'means is a hollow screw, single screw means for supporting said bell'eomprising a screw extending through said hollowqscrew-having a threaded portion. extending through said base ed to cooperatewith a detachable connector'cle'r vice secured to said terminal block, said strips being formed so as'to extend from said terminal f, 1 block through said base member and project from the'under side thereof substantially at right anglesthereto. I V Y 5. An electric-bell according toclaim l in which a pair of upwardly extending bosses arelformed in said base'member, a hole through "each boss,

"a threadedmember having a collar in substan tially the midportionthereof projecting upward through each of said holes, the collarportion of each threaded member being disposed within'the respectivebosses, means for securing the bridge'f to the portion of the threaded membersprojecting through said Tbosses thereby securing said is turned over at 98 to overlap theedge of disc I 92., The guard member is slotted at, 99 in the threaded members to. said base member," and means tosecure the baseof a guard member to lower half th'ereoff and 'an openingrlllllj'ispro vided in the top thereof to permit access toscrew" i M-byWhich t-he entire structure maybe-fastened basemember portion adapted to overlie thenuppervsurface of theizbaseinfgember and :fa. tuyzued. rovep edge on said flangearranged,to fit pvterjheedw 0i said Ar;v electric: b

i r 2-13 5: fliepppbsite end portions of'said vthiiea,glgagl Vmem:

' 6; lectric bell accbrdingitq claim :1 where- V V in said casing comprises a, cylindrigal wallpor' I ;tic n, a. flange formedat the edge Q15v said wall thekbase member, a "turned over edge on -gsaid mu s firralgg'ed to fit Over the edge of saiibase membegg a ring-shamed gasket disposed between saidgflange andrigsaid base member held in tight en ageme ti a w h b y: i n scre 

